The invention relates to a filter ventilator according to the precharacterizing clause of claim 1. The invention further relates to an exhaust filter according to the precharacterizing clause of claim 24.
Filter ventilators are required for the ventilation of switch cabinets, circuit boxes, device housings and the like. In particular electronic components integrated into switch cabinets generate large amounts of heat. Overheating can damage electronic elements, in particular semiconductor elements, or even destroy them. Ventilation of such switch cabinets counteracts excessive heat development. For this purpose, a ventilator is used to suck in the outside air and blow it into the interior of the cabinet. By way of one or more exhaust openings in the walls of the switch cabinet, the warmed air is blown out again. Hence there is a heat exchange between the air in the cabinet and the external air.
In the external air dust particles are always present. Often it is necessary for the switch cabinets to be set up in particularly dusty surroundings. Therefore it is advantageous to insert a filter ahead of the ventilator, so that the air that is being sucked in first passes through the filter and then the ventilator, before entering the cabinet. Having been warmed in the interior of the cabinet, the air is expelled to the exterior by way of the exhaust openings. The filter ventilators are customarily installed in stamped-out or nibbled-out openings in the cabinet wall.
Especially in dusty surroundings, the filters must be exchanged relatively frequently. Although the ventilator motors have a relatively long working life, in the case of long-term operation motor failure can also be expected to occur, so that the ventilator motors must also be exchanged.
Replacing the motor of the known filter ventilators is a relatively elaborate process. The motor is in the interior of the switch cabinet and is accessible only from there, whereas the means by which the motor is mounted are accessible only from outside. Therefore two people are needed to exchange a motor: one to manipulate the attachment means from outside, while the other holds the motor from inside, so that a great deal of effort is required. Furthermore, for reasons of safety it can be necessary for the electronic components to be turned off before a person reaches into the interior of the switch cabinet.
The initial installation of the known filter ventilators in the aperture in a wall is also relatively complicated. Again, at least two people are needed so that the installation can be carried out from two sides of the wall.
Furthermore, it is desirable for the switch cabinets to be sealed to prevent electromagnetic waves from radiating inward or outward. Shielding to ensure electromagnetic compatibility is difficult when a cabinet is simultaneously being ventilated. EMC-shielded ventilators are known in which grids are disposed between the filter and the ventilator motor. These grids are connected by strips of sheet metal to contact strips mounted on the back side of attachment flanges for the ventilators. With such shielding there are regions where the EMC seal is incomplete, so that it often does not satisfy the requirements. For optimal EMC shielding it is necessary for the entire periphery of an aperture in the wall of the switch cabinet to be electrically connected to the grid. To achieve this, in the known apparatus the cabinet wall must have an exposed surface around the aperture. Because the wall of a switch cabinet is generally lacquered, the lacquer must be removed before a ventilator is installed. In the case of the known ventilators this applies to the inner surface of the cabinet wall. Both the initial installation of such ventilators and the replacement of the ventilator motors or filters are thus very elaborate processes.
It is the objective of the invention to make available a filter ventilator that can be installed and removed in a simple manner, and in which the ventilator motor and the filter can be exchanged from one side of the wall, by a single person.
A further objective of the invention is to make available a corresponding exhaust filter.
For the filter ventilator this aim is achieved by the object with the characteristics given in claim 1. In the case of the exhaust filter, it is achieved by the object with the characteristics given in claim 24.
In accordance with the invention the filter ventilator is provided with a build-in frame and an insertion frame, such that the build-in frame comprises attachment means and can be permanently installed in the aperture, the insertion frame is removably inserted into the build-in frame, the ventilator motor is releasably connected to the insertion frame and the filter is removably inserted into the insertion frame.
It is thus provided that when the filter ventilator is first installed in the aperture of a wall, the build-in frame is permanently fixed within that aperture by attachment means. The insertion frame is set into the build-in frame so that it can be removed and needs to be taken out of the build-in frame only when access to the reverse side of the ventilator motor is required, or the motor must be replaced. The filter is merely removably set into the insertion frame in front of the motor, from the viewpoint of the operator, so that when the filter must be exchanged, the insertion frame can remain in place within the build-in frame. Therefore the initial installation of the filter ventilator in the aperture of a wall, the exchanging of the filter and the replacement of the ventilator motor can be undertaken by a single person and from a single side of the wall, in particular from the outside of the wall. A commercially available ventilator motor can be used, which is obtainable on site.
It is preferably provided that between the ventilator motor and the filter a grid is disposed, which extends within the insertion frame parallel to the plane of the frame. This grid ensures the spatial separation of the filter from the ventilator motor, in particular with respect to the fan blades. Penetration of filter particles into the ventilator motor is thereby prevented or at least restricted.
Preferably it is provided that the insertion frame is constructed in one piece with the grid. This contributes to the stability of the insertion frame. An insertion frame of this kind can be manufactured simply and economically.
It can further be provided that the insertion frame comprises first spacer elements, so that there is a predetermined distance between the grid and the filter. By this means an empty space is left between the grid and the filter, which acts as a pressure-equilibration or turbulence space. Hence the air flows uniformly through the filter, which results in a low pressure loss and an optimal utilization of the filter.
Similarly, it can be provided that the insertion frame comprises second spacer elements, so that there is a predetermined distance between the grid and the ventilator motor. This cavity also causes the pressure loss of the airstream to be relatively low.
In an especially preferred embodiment of the invention it is provided that the build-in frame, the insertion frame and the grid are made of metal, or at least their surfaces have a metal coating. These measures allow the filter ventilator to be tightly EMC-sealed. For many switch cabinets or the like it is required, or at least desirable, that no electromagnetic radiation passes inward or outward through their walls. In this respect the aperture constitutes a weak point, which is eliminated in particular by the metallic or metallized grid. The switch cabinet can therefore be ventilated and simultaneously achieve the required EMC impenetrability.
It is further provided that the insertion frame be releasably attached within the build-in frame by means of a clamping device. To release a clamping device, in general no tools or only simple, standard tools are needed, so that the insertion frame can rapidly and simply be removed from the build-in frame and replaced therein.
In particular it is provided that the clamping device is composed of a large number of flexible tongues. Preferably these tongues are disposed at the periphery of the insertion frame and extend perpendicular to the plane of the frame. The tongues act as springs, ensuring that the insertion frame is securely held within the build-in frame. Furthermore, the tongues form a continuous electrical contact between insertion frame and build-in frame, extending around the entire periphery. This makes a substantial contribution to the EMC seal.
It is further provided that the build-in frame comprises a flange on which the attachment means can be mounted. A flange enables the build-in frame to be installed especially simply within the aperture in the wall, and guarantees a secure seating. Furthermore, the flange makes a considerable contribution to the EMC seal.
Preferably it is provided that the attachment means are adhesive strips. Adhesive strips enable a particularly simple installation of the build-in frame within the aperture in the wall and provide a secure seating. In addition, they do not require any holes to be drilled in the wall. Furthermore, adhesive strips constitute a water-tight connection, at least one through which splashed water cannot penetrate.
It is further provided that the build-in frame comprises a contact band with teeth, which extends along the periphery of the build-in frame in such a way that the teeth can be brought into engagement with the edge of the aperture. As a result, an electrical connection is ensured between the wall and the build-in frame over the entire periphery of the build-in frame and the entire edge of the aperture. The contact band thus contributes substantially to the EMC seal. Furthermore, the contact band considerably facilitates the initial installation of the filter ventilator in the wall. Because of the teeth on the contact band it is not necessary to remove the lacquer from the wall of the switch cabinet, as must be done in the state of the art. The contact band with teeth, which are made for example of copper beryllium, is commercially available. The teeth cut into the edge of the aperture, which has been left exposed following the nibbling or cutting, and fit closely there. The contact band thus creates an optimal electrical contact between the wall and the build-in frame.
For the ventilator motor is it provided that it is attached to the insertion frame by means of screws. This screw attachment ensures an adequately secure mounting and enables rapid and simple replacement of the motor.
It is further provided that the ventilator motor is attached to the insertion frame by means of self-tapping screws, such that the internal threads cut by the screws are disposed on the insertion frame, in particular in the grid. During the manufacture of the insertion frame or grid, therefore, no threaded bores or the like need be constructed. Nor are nuts or the like required.
As a result, the number of individual parts of the filter ventilator is kept small. This contributes to an economical manufacture of the ventilator.
In an especially preferred embodiment of the filter ventilator, it is provided that the insertion frame is made of injection-molded plastic. Plastic parts can be simply and economically constructed by injection molding and their surface can be coated with metal. By this means the electrical conductance and hence the EMC sealing can be ensured in a simple and economical manner.
It is further provided that the filter ventilator comprises a covering cap that is releasably fixed to the insertion frame, such that the filter is disposed between insertion frame and covering cap and the covering cap comprises a region through which air can flow. The cap has both technical and aesthetic functions. For the covering cap it is preferably provided that the air-permeable region comprises plurality of lamellae, which are oriented in such a way that the air sucked in between them flows in the upward direction. As a result, the number of dust particles that are sucked in is minimized and splashed water is largely prevented from penetrating into the interior of the ventilator.
For an alternative embodiment of the ventilator in accordance with the invention it can be provided that the build-in frame is dished, such that the wall of the dish encloses the ventilator motor and there is at least one region through which air can pass. The dish shape of the build-in frame eliminates the possibility that the ventilator motor might fall down into the interior of the switch cabinet during the installation work. If the build-in frame is made of metal or at least has a metallic surface, the EMC sealing of the ventilator is additionally increased thereby. Furthermore, shielding between the ventilator motor and the interior of the switch cabinet is thus achieved. Preferably the air-permeable region of the dish region is formed by an additional grid. A grid on one hand allows a high throughput of air, and on the other hand produces tight EMC sealing.
For the exhaust filter in accordance with the invention it is provided that the exhaust filter is constructed like the filter ventilator described above except that it does not comprise a ventilator motor with fan blades. By simply eliminating the ventilator motor, an exhaust filter can be produced instead of a filter ventilator. From the standpoint of manufacturing technology, this is an especially simple and economical solution. The exhaust filter requires no additional parts.
For another embodiment of the filter ventilator in accordance with the invention it can be provided that instead of a single ventilator motor, the ventilator comprises several motors disposed side by side. Preferably these are arranged as a matrix and are constructed as axial ventilators. This embodiment has the advantage that the ventilator can be of very flat construction. Furthermore, the filter ventilator remains functional even if one motor should stop working.
Other characteristics, advantages and special embodiments of the invention are the subject matter of the subordinate claims.